Enhanced Photostability from CdSe(S)/ZnO Core/Shell Quantum Dots and Their Use in Biolabeling

Abstract

Abstract We report on the preparation and on the photophysical and structural characterization of alloyed CdSe(S) nanocrystals, which are covered by a ZnO shell. CdSe(S) QDs were prepared by reaction of CdCl 2 with NaHSe in the presence of 3‐mercaptopropionic acid (MPA) under hydrothermal conditions. The incorporation of sulfur arises from the surface‐mediated MPA hydrolysis on the growing QD surface. Water‐dispersible CdSe(S) QDs were successfully capped with a ZnO shell obtained by basic hydrolysis of Zn(OAc) 2 . The experimental results from transmission electron microscopy (TEM) imaging and powder X‐ray diffractometry (XRD) analyses indicate that the core/shell CdSe(S)/ZnO QDs have a very small diameter (ca. 2.8 nm) and exhibit a face‐centered cubic crystal structure. Our results show that core/shell CdSe(S)/ZnO QDs have a higher photostability than CdSe(S) cores. CdSe(S)/ZnO QDs have potential applications asfluorescent biological labels and were successfully used for imaging Schewanella oneidensis bacterial biofilms.